Finally got a reply from blizzard and this wot they said:
"Greetings,
Thank you for your email. There are a few things which can impact or even prevent Voice Chat from working properly in StarCraft II.
1. Drivers update
Be sure you have the latest sound and motherboard drivers. More information on identifying your sound driver version can be found at:
http://eu.blizzard.com/support/article.xml?articleId=22628
Motherboard drivers should be available on your motherboard or system manufacturer's site. Links to manufacturers' web sites can be found at:
http://eu.blizzard.com/support/article.xml?articleId=22630
2. Sound and microphone settings
The first thing we would recommend checking is to make sure normal sound works in other applications. Please make sure that you can play sounds using your favourite media player and your web browser. If those don't work make sure the system volume is turned up and that your speakers are plugged into the correct slot for your computer.
Then please make sure the microphone is working as well. If not we recommend you to contact the computer manufacturer in order to troubleshoot issues with the microphone.
3. Windows Vista / Windows 7 Sound
Windows Vista and Windows 7 handle volume on a per-application basis when the application is running. It is possible that StarCraft II is muted whereas other applications are not. When StarCraft II is running and you are not logged onto Battle.net please press Alt and Tab to minimize the game, click the speaker icon then click the Mixer link. In that list you will need to look for StarCraft II, verify it is not muted and that it is turned up.
Next you will need to check in-game settings.
4. In-Game Voice Chat Settings
From the main menu select options then voice. Please make sure that "Enable Microphone" is checked. The dropdown menu should be set to "Default" and the volume slider should be set to the right, at 100%. Once those are all set click "Okay", bring up Sound and Voice again and perform the microphone test, both recording and playing back.
5. Firewall and Router Settings
If the 'microphone test' in game is working fine and you can hear yourself but not others (or others cannot hear you), that is a good indication that a firewall or router is causing the issue.
Some routers and firewalls may block just the voice chat functionalities of StarCraft II . You will need to ensure your router is forwarding UDP ports 1119 and 1120 to your computer's private IP address; please refer to your router's manual to correctly configure the required port numbers. Also please make sure your software firewall is not preventing StarCraft II from receiving incoming connections.
Should none of the steps above help we will need you to reply to this email with your dxdiag.txt and msinfo.txt diagnostic files:
http://eu.blizzard.com/support/article.xml?articleId=19397
Please also attach your StarCraft II Log file:
- Right Click on the StarCraft II icon
- Choose Properties
- Click the "Find Target" button (or "Open File Location" in Vista) on the Shortcut tab
Then locate the Logs folder in the new window that appears and attach to your reply any text documents from inside.
Should you need further technical assistance, please do not hesitate to contact us again.
Best regards,
Christian A.
Billing Support
Blizzard Entertainment Europe
<http://eu.blizzard.com/support>
Telephone Number:
<http://eu.blizzard.com/support/article.xml?articleId=23210>
Please retain all history when you reply to this email"
not much help from them
